In the field of steel sheet for automobile use, to lighten the weight for improving fuel efficiency and to improve the impact resistance, application of tailored blanking has been spreading. “Tailored blanking” means the process of press-forming a sheet member comprised of a plurality of metal sheets differing in material, thickness, tensile strength, etc. joined by butt welding (below, “tailored blank material”) into a desired shape. For the butt welding when producing the tailored blank material, laser welding is generally used.
PLTs 1 to 3 disclose methods of butt welding using laser welding so as to produce a tailored blank material.